Figure 7: Measurement of GSH in the presence of various inhibitors and expression of genes involved in GSH metabolism. (a) HepG2 cells were treated with 40 μM alantolactone for 6 h in the presence or absence of various inhibitors and concentration of GSH was measured according to kit instructions. Data are expressed as mean ± SD (). Columns not sharing the same superscript letter differ significantly (). (b) Cells were treated with 40 μM alantolactone for indicated time points and cell lysates were subjected to Western blot analysis for the expression of glutathione reductase (GR). (c) Cells were treated with 40 μM alantolactone for indicated time points and mRNA expression of γ-glutamyl cysteine synthetase (γ-GCS) was determined by RT-PCR. (d) Alantolactone (1 mM) was incubated with indicated concentrations of GSH in medium for 30 min and amount of alantolactone was assessed using HPLC. The data shows that GSH decreased the amount of alantolactone in a dose-dependent manner. Data are expressed as mean ± SD (). Columns not sharing the same superscript letter differ significantly ().